Question

`E^(@) (SRP)` of different half cell given
`{:(E_(Cu^(2+)//Cu)^(@) =0.34"volt",,,E_(Zn^(2+)//Zn)^(@) =- 0.76"volt"),(E_(Ag^(+)//Ag)^(@) = 0.8"volt",,,E_(Mg^(2+)//Mg)^(@) =- 2.37 "volt"):}`
In which cell `Delta^(@)` is most negative:-
A. `Zn|Zn^(2+)(1 M)||Mg^(2+)(1 M)|Mg`
B. `Zn|Zn^(2+)(1 M)||Ag^(+)(1 M)|Ag`
C. `Cu|Cu^(2+)(1 M)||Ag^(+)(1 M)|Ag`
D. `Ag|Ag^(+)(1 M)||Mg^(2+)(1 M)|Mg`

Answer 1

Correct Answer - B
(b) (a)`Zn|Zn^(2+)(1 M)||Mg^(2+)(1M)|Mg`
`E_(cell)^(@)=E_(cathode)^(@)-E_(anode)^(@)=E_(Mg^(2+)//Mg)^(@)-E_(Zn^(2+)//Zn)^(@)`
`=-2.37-(-0.76)=-1.61" V"`
`DeltaG^(@)=-nFE_(cell)^(@)=-2xx96500(C )xx(-1.61" V")`
`=+310,730" CV"=+310.730" kJ"`
(b) `Zn|Zn^(2+)(1 M)||Ag^(+)(1 M)|Ag`
`E_(cell)^(@)=E_(Ag^(+)//Ag)^(@)-E_(Zn^(2+)//Zn)^(@)`
`=0.80-(-0.76)=+1.56" V"`
`DeltaG^(@)=-nFE_(cell)^(@)=-2xx96500" C"xx1.56" V"`
`=-301,080" CV"`
`=-301.08" CV"`
(c )`Cu|Cu^(2+)(1 M)||Ag^(+)(1M)|Ag`
`E_(cell)^(@)=E_(Ag^(+)//Ag)^(@)-E_(Cu^(2+)//Cu)^(@)`
`=0.80-0.34=+0.46" V"`
`DeltaG^(@)=-nFE_(cell)^(@)=-2xx96500" C"xx-0.46" V"`
`=-88,780" CV"=-88.780" kJ"`
(d)`Ag|Ag^(+)(1 M)||Mg^(+)(1M)|Mg`
`E_(cell)^(@)=E_(Mg^(2+)//Mg)^(@)-E_(Ag^(+)//Ag)^(@)`
`=-2.37-0.80=-3.17" V"`
`DeltaG^(@)=-nFE_(cell)^(@)=-2xx96500" C"xx(-3.17" V")`
`=+611,810" CV"=+611.0810" kJ"`
(b) has maximum negative `DeltaG^(@)` value.